Surface heating unit with improved hinge and ground connection



Dec. 8, 1953 B. J. VALLORANI SURFACE: HEATING UNIT wIIU IMPROVED HINGE: AND GROUND CONNECTION Filed July 2e 1951 NY/IHN!! 25 Patented Dec. 8, 1953 UN I'TED STATES PATENT OFFICE SURFACE HEATING UNIT Wl-TH IMPROVE!) .AND GROUND .COPUNEC.f1-10N Ben J. Valloran-i, Melrose Park, Ill., assignor to General Electric Company, a corporation of New York Application July v.28, 195.1, Serial No. 239,117

4 Glaims.

l This` invention relates to heating deyicessuch as the surface heatingsunits. of electricv ranges, and it is an object-of my inventionto provide surface heatingunits havingan improved 'hinge .and groundv connection for .pivotally supporting the surface unit andgrounding the heating elements thereof tothe. range frame.

Electric range surface heating units now commonly .use heating elementsr of the sheathed conductor type .as described, for example, in the C.

C. Abbott U. S'. kIYatellt -#71,367,341- datedFebruary 1, 1921, and in .the J. C.. ,Sharp Reissue Patent #22,177 yof .september a, 1942. The elements comprise va coiled resistance conductol` housed in la metallic .sheath and supported in insulated spaced relationship therewith 'by a densely compacted body of ,heat-conducting and electrically insulating material,.such las .powdered magnesium oxide. .The velements are .arranged in a dat coil pattern .on.a suitable support structure, with the terminalends .of the coils extending to a point of connection with the .wiring system oflthe range, usually beneath ther range cooking top. Itis` the accepted practice tohingedly secure the surface heating units to the range so 'that the units may be. swung upwardly forcleaningoor otherpurposes.

.It ,is .advantageous to secure the 'heating .ele-

ments to .the support structurein `a manner allowing them maximum freedom of movement so that .they mayV expand .and contract relatively Ifreely .under temperature .changes in use; and .where practicable, 'it isdesirable 4to `Secure the rheating elements to the support structure at Vone ,p 'oint only, thus `permitting maximum 'freedom consistent with proper seeurement to wthe support. My present invention provides a heating unitvv in "which the terminal ends-of the heating 'element are' arranged `rorfree movement, and the unit is secured to the range -frameand grounded in a mannercontributing 'to such :freedom while at the-Sametime-k resiliently restraining certain Lof: .the aterminal ends 'against being lifted Arelative tothe support' structure. Specifically', 1I. use a vhinge having Lone element ii-xed tothe frame of .the range in electrically conductive relation, and another element `rigidly attached to 'the v.support structure. A 1grounding member is welded .or otherwise secured .tothe second-namedhinge element and has a vresilient conductorstrip which extends parallel to a terminal portionof a heat- 'ing element and permits movement of ithe terminalportion under normal heating and cooling conditions. Because f the flexible grounding Fstrip -is'fan integralipart of {the-hinge, it swings-with-t-he hinge when the surface unit israisedand thereing top .opening ll. 4securing :theisupport Ystructure to the trim ring fore is not subjected to strains which might break or weaken the :bond with the sheath of theheatine element.

'In the .accompanying drawings, Fig. 1v is -a fragmentary plan` view of a sur-face heating unit utilizing la preferably preferred form of my hinge and ground strap; Fig. 2 is a side sectional elevation of the complete 'heating unit taken along the lines 2-2 of Fig. 1; Fig. 3 is a fragmentary end sectional elevation of the terminal portion c1e lthe heating elements, the terminal housing having `been removed; and Fig. ll is a perspective -l-view of the combined hinge and ground strapseaforementioned Abbott or Sharp type, pursuant to 4which each element -has alcoiled resistance conductor llihoused in a metallic sheath il and supported-in `uniformly spacedrelationship to the lshea-th by-a highly compacted mass I2-of -a Ysui-table` heat-conducting and electrically insulating material-,suchas powdered magnesium oxide. As is conventional,-the heatingelements are arranged to yform `fiat spirals of lseveral coils and are ynested one 4within the other on a support structure which may include a plurality of' radially -extending, `inertically arranged, plates M,

Ida, -l5',- 5a, -andl Srita Ajoined ltogether at acentr-all hub vand extending radially therefrom. Upper edges of these plates -lie `in a common plane and vsupport :the heating elements as shown.

Thesupport structure is carried by Va trim ring havingfalhorizontal-rim Il resting onthe cooking top I about the opening thereinfanda downwardly-:extending `iiange I8, which is spaced inwardly from the depending flange lSfdening the cook- An advantageous manner Vof is: by providingfeach ofthe support varms with a Ashortitongue 12d brought through a suitable slot inthe trim ringwall i8. The trim ring thus es- -ftablishes vthe plane ofthe upper edges ofthe sup- Y portarms parallel tothe-plane of the cooking'top fl. A drip` and reector pan 2| is vsuitablyn 11- movably supported below the heating unit as on an inwardly turned lip (see Fig. 2) at the base of the flange I9.

The respective heating elements rest on the upper edges of the support arms, and each element is secured to one only of the arms at only one point. As shown in Fig. 2, an outer convolution of each of the heating elements is anchored to the support arm I5a by an anchor plate 22 secured to the support arm and having upwardly extending pairs of jaws which grip the sheath of the respective heating elements. Except for this single point of attachment of the heating elements to the support structure, the elements are free to move on the upper edges of the supporting structures as they expand and contract with temperature changes. The terminal ends of the heating elements extend downwardly from the support arms and then through an opening 23 in the reflector pan 2|. The terminal portions of the sheathed conductors extend for a substantial distance below the cooking top l and are provided with the illustrated exposed terminals 5, 5a, Ea, 8a, 9a. Terminals 6a and 9a have individual connection fittings 24, 25 to which the leads (not shown) of the rangewiring system may be attached by means of conventional binding screws 26; and as part of a conventional wiring circuit which provides for several levels of thermal output, the terminals 5a. and 8a are permanently interconnected by a bus bar having the common connection fitting 21 as shown in Fig. 1.

It is a feature of my construction that the terminals are given maximum freedom of movement. Therefore, instead of the usual unitary drip shield which embraces all of the terminal portions, I apply individual metal drip shields 28 which tightly engage the outer sheath of said terminal portions. It will be noted that the terminal portions 6 and 9 may move relative to each other, and each of these terminal portions has freedom of movement relative to the terminals 5 and 8. Consistent with the objective of maximum freedom of movement, I use a porcelain terminal spacer block 29 which Slips over the terminal ends of the terminals and is loosely held thereon merely by resting upon the heads of the connection screws. As is shown in Figs. 1 and 2, this block 29 is provided with wall means which l define pockets accommodating the terminals.

It has previously been noted that each heating unit is hingedly mounted on the range frame; and it is well known that the sheaths of the individual heating elements must be grounded to eliminate shock hazard. I have provided a simple, effective, hinge having grounding means constructed as an integra1 part thereof, and have arranged said grounding means so that the terminal ends of the sheath have maximum freedom of self-adjustment and at least one terminal end of each heating element is resiliently restrained against accidental displacement relative to the support structure.

Referring now to Figs. 2 and 4, the combined` hinge and ground strap 30 includes a hinge element comprising a rigid base plate 3 I, from which extends, preferably upwardly, a pivot plate 32, and spaced, rigid, attachment strips 33, 33a which are arranged to lie flush against the flange I9 around the cooking top opening. It will be understood that the cooking top comprises an element of the range frame and that when the range is installed its frame is electrically connected to ground by suitable means (not shown).

. respect to the other.

4 The hinge element is rmly secured to the range frame element by a self-tapping screw 34 or equivalent fastening means which will make electrical contact with the metal of the range frame, specifically with the base metal of the flange I9. The upper ends of the strips 33, 33a. are curved to conform to the curved transition between the flange i9 and the cooking top; and with the illustrated stiffening ribs provided in base plate 3l, which abut the lower edge of iiange i9, provide means for quickly and easily locating the hinge element on the range. As shown in Fig. 3, the spacing between the strips 33, 33a easily accommodates the shank of screw 311, but provides 1 for substantial engagement of the screw head with the plates. A washer (not shown) may be used beneath the screw head if desired, although experience indicates that it is unnecessary.

rhe complementary hinge member may advantageously comprise a rigid bar having an integral pivot plate 35 and an integral securement plate 36 at its respective ends. Plate 3E is preferably riveted to support arm I5, although it may be welded or otherwise secured thereto. Intermediate these plate-like members, the bar is shaped as necessary to position its longitudinally extending pcrtion 31 substantially in the plane of the respective terminal portions 5, B, 8, and 9 of the heating elements and in relatively close,

laterally spaced, relationship to one of said terminal end portions. For example, in a surface unit having only one heating element, the portion 31 might be relatively close to one of the terminal end portions and widely spaced with In the illustrated two-element embodiment, the portion 31 runs centrally between the adjacent terminal portions 5 and 8. The respective hinge elements are pivotally joined by a metallic rivet extending through the pivot plates 32 and 35. I prefer to use a conventional frusto-conical metal friction washer 49 between the pivot plates so that the heating unit will be frictionally held in any position between its normal operating position and any raised position.

To ground the heating element sheaths while affording adequate freedom of movement of the terminal ends and providing resilient means to restrain separation of ons end of each of the heating elements from the support structure, I use a novel ground strap having flexible members which run parallel to the terminal portions, and provide electrical connection between the rigid bar-like hinge element and the terminal sheath.

, As shown best in Fig. 4, the grounding means comprises a generally U-shaped metallic structure having a base portion 4I welded to a dat formed in the underside of the portion 31, and flexible strips 42, 43 preferably integral with the base 4I and extending beneath the terminal portions 5 and 8 in relatively close spaced relation, as appears in Fig. 2. So as to space the flexible strips suitably below the terminal portions, the base 4I is formed with suitable offsets, as indicated in Figs. 3 and 4. The downwardly extending tips 42a, 4ta of the strips are welded to the drip shields of the terminal portions 5 and 8, and a positive electrical connection is thus made from the sheath of each heating element through the ground strip, the hinge, and screw 3Q to the metal of the range frame. Although I have illustrated the grounding element as being of sheet metal stock, it is obvious that it might comprise a `U- shape of spring wire, or that the strips 42, 43

mightbereplacedyby spring wire-lengthssuitably secured to,a.base,portion 4 I It should be-noted-that 'thek respective heating elements, being in at coil form, have an-inherent resiliencyc.' Because. of this; it; may happen-that one or the other of; the. terminal portions: of

leach. element. may. takef. a` set` during its manufacture .whichicauses ashort length ofz'thesactual operating portion of the, element to lift above the support structure when the element is staked t the support member |5212 `I have found'thati it is usuallypossible totruefup-the elements'i-after staking by manually adjusting a terminal portion of one heating element with respect to its companion terminal portion. Also, I have found that occasionally the elements may be trued up by adjusting the terminal portion 5 of one element with respect to the terminal portion 8 of the other. In either case, it is advantageous to make this adjustment at the portions 5 and 8 by suitably bending the rigid bus bar 21. The flexibility of the ground strips 42, 43 permits such adjustment and serves to restrain the separation of these terminal portions from the support structure.

When the surface unit is in use the heating elements expand and contract, and in former constructions it was found that the rigid restraint of the ends of the heating elements (see, for

example, the rigid interconnection of the heating g,

element terminals by the unitary drip shield in the above-noted Sharp Reissue Patent #22,17'7) will cause intermediate portions of the heating elements to loop upwardly at some point along their operative length. In practice, this seriously y,.-

aifects the eiciency of heat transfer between the heating element and the cooking vessel placed thereon because an upwardly looping portion of an element will lift the bottom of the pan out of contact with a large portion of the heating surface. In the present invention, however, the complete freedom of the terminal ends 6 and 9, plus the large amount of freedom and flexibility afforded by the ilexible ground strips at terminal ends 5 and 8, permit expansion and contraction of 3 the elements while maintaining them in the horizontal plane of the support structure.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various modifications may be made therein, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention,

I claim:

1. A surface heating unit for an electric range or the like, comprising, in combination, a support structure, a plurality of coiled tubular sheath heating elements mounted thereon, a single means secured to said support structure and engaging the sheath of each of said heating elements at one point only to secure the same to said support structure, said heating elements having rectilinear terminal portions extending in substantially parallel relation beyond said support structure, at least two of said terminal portions being structurally independent for movement relative to each other, a metallic hinge member having pivotally associated hinge elements respectively secured to said range and to the support structure, said hinge member being electrically connected to said range, and metallic ground strap means including a cross member rigidly electrically connected to, and extending angularly with respect to, said last-named hinge eletrically lconnected to the sheath frange` havingJ ametalli'c Abody structure; said l()v heating unit "including al heatingleleme'nt Icomprisinga lresistance conductor having ajcoextensive -metailic Asheathl electrically `insulated therefrom, terminal portions' of` said"V metallic sheatlibeirrg inirelatively 'close proximity' to' "said "range body"'struct`u're and having' relatively'v free movement. with. respect thereto, and' means including Aari'gld structural element secured to said metallic sheath intermediate the ends thereof for supporting said heating element relative to said range structure: a combined hinge and ground strap including a first metallic hinge member secured to said range body structure in electrically conductive relation therewith, a second metallic hinge member conductively pivotally attached at one end to said rst member and secured at its other end to said structural element, said second hinge member extending longitudinally of at least one terminal portion of said metallic sheath in spaced relation therewith, a flexible conductor element secured at one end in conductive relation to said second hinge member intermediate the ends thereof and extending parallel to said one sheath terminal portion, and means for connecting the opposite end of said flexible conductor element in permanent electrically conducting relation to said metallic sheath at said terminal portion thereof.

3. For use with an electric range surface unit including a tubular sheathed heating element and support means for positioning said heating element substantially in the plane of an upper frame panel of said range, said support means having a rigid structural member and said heating element having substantially mutually parallel terminal portions extending therefrom below said structural member; a combined hinge and ground strap for pivotally mounting said unit relative to said range frame panel, comprising a metallic hinge member adapted to be secured to said range frame in electrically conducting relation therewith, a rigid metallic arm member pivotally attached to said hinge member and adapted for securement to said support means, and a relatively long, springable, metal ground strap fastened at its respective ends to said hinge arm member and to the sheath of a terminal portion of said heating element, the intermediate portion of said ground strap extending axially along said sheath in spaced relation thereto, said ground strap resiliently resisting the separation gf said heating element from said support strucure.

4. For use with an electric range surface unit including a tubular sheathed heating element and support means for positioning said heating element substantially in the plane of an upper frame panel of said range, said support means having a rigid structural element and said heating element having a plurality of substantially mutually parallel terminal portions extending therefrom below said structural element; a combined hinge and ground strap for pivotally mounting said unit relative to said range frame panel, comprising a metallic hinge member adapted to be secured to said range frame in electrically conducting re- Taeeairs'r lation therewith, a rigid, metallic, arm member pivotally attached to said hinge member and extending between adjacent terminal portions, said Asheath of a different one of said terminal portions and resiliently resisting vertical movement of said terminal portion relative to said hinge 15 arm member.

BEN J. VALLORANI.

References cited in the me of this patent UNITED STATES PATENTS Number Number Name Date Morton Apr. 8, 1947 Walton et a1. Apr. 10, 1951 Vogel et al Aug. 21, 1951 Schulze Feb. 12, 1952 FOREIGN PATENTS Country Date Germany Sept. 24l- 1936 

